Touch sensitive actuator having a uniform actuation force and a maximum active area

ABSTRACT

A load control device for controlling the amount of power delivered to an electrical load from an AC power source comprises a touch sensitive device having a touch sensitive front surface responsive to a point actuation. The front surface is adapted to be provided in an opening of a faceplate such that the front surface of the touch sensitive actuator extends through the opening at a distance equal to or greater than the depth of the faceplate. According to the present invention, the operational area of the front surface is maximized to substantially the entire area of the front surface. Further, a minimum magnitude of a force of each of the point actuations is substantially equal at each of the respective positions on the front surface of the touch sensitive actuator, such that the front surface provides a substantially uniform force profile.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation under 37 C.F.R. § 1.53(b) ofapplication Ser. No. 11/472,239 filed Jun. 20, 2006, by Gregory ALTONEN,entitled TOUCH SENSITIVE ACTUATOR HAVING A UNIFORM ACTUATION FORCE AND AMAXIMUM ACTIVE AREA, the entire contents of which are herebyincorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to load control devices for controllingthe amount of power delivered to an electrical load from a power source.More specifically, the present invention relates to a touch dimmerhaving a touch sensitive device.

2. Description of the Related Art

A conventional two-wire dimmer has two terminals: a “hot” terminal forconnection to an alternating-current (AC) power supply and a “dimmedhot” terminal for connection to a lighting load. Standard dimmers useone or more semiconductor switches, such as triacs or field effecttransistors (FETs), to control the current delivered to the lightingload and thus to control the intensity of the light. The semiconductorswitches are typically coupled between the hot and dimmed hot terminalsof the dimmer.

Smart wall-mounted dimmers include a user interface typically having aplurality of buttons for receiving inputs from a user and a plurality ofstatus indicators for providing feedback to the user. These smartdimmers typically include a microcontroller or other processing devicefor providing an advanced set of control features and feedback optionsto the end user. An example of a smart dimmer is described in greaterdetail in commonly assigned U.S. Pat. No. 5,248,919, issued on Sep. 28,1993, entitled LIGHTING CONTROL DEVICE, which is herein incorporated byreference in its entirety.

FIG. 1 is a front view of a user interface of a prior art smart dimmerswitch 10 for controlling the amount of power delivered from a source ofAC power to a lighting load. As shown, the dimmer switch 10 includes afaceplate 12, a bezel 14, an intensity selection actuator 16 forselecting a desired level of light intensity of a lighting load (notshown) controlled by the dimmer switch 10, and a control switch actuator18. Actuation of the upper portion 16A of the intensity selectionactuator 16 increases or raises the light intensity of the lightingload, while actuation of the lower portion 16B of the intensityselection actuator 16 decreases or lowers the light intensity. Theintensity selection actuator 16 may control a rocker switch, twoseparate push switches, or the like. The control switch actuator 18 maycontrol a push switch or any other suitable type of actuator andtypically provides tactile and auditory feedback to a user when pressed.

The smart dimmer 10 also includes an intensity level indicator in theform of a plurality of light sources 20, such as light-emitting diodes(LEDs). Light sources 20 may be arranged in an array (such as a lineararray as shown) representative of a range of light intensity levels ofthe lighting load being controlled. The intensity level of the lightingload may range from a minimum intensity level, which is preferably thelowest visible intensity, but which may be zero, or “full off,” to amaximum intensity level, which is typically “full on.” Light intensitylevel is typically expressed as a percentage of full intensity. Thus,when the lighting load is on, light intensity level may range from 1% to100%.

By illuminating a selected one of the light sources 20 depending uponlight intensity level, the position of the illuminated light sourcewithin the array provides a visual indication of the light intensityrelative to the range when the lamp or lamps being controlled are on.For example, seven LEDs are illustrated in FIG. 1. Illuminating theuppermost LED in the array will give an indication that the lightintensity level is at or near maximum. Illuminating the center LED willgive an indication that the light intensity level is at about themidpoint of the range. In addition, when the lamp or lamps beingcontrolled are off, all of the light sources 18 are illuminated at a lowlevel of illumination, while the LED representative of the presentintensity level in the on state is illuminated at a higher illuminationlevel. This enables the light source array to be more readily perceivedby the eye in a darkened environment, which assists a user in locatingthe switch in a dark room, for example, in order to actuate the switchto control the lights in the room, and provides sufficient contrastbetween the level-indicating LED and the remaining LEDs to enable a userto perceive the relative intensity level at a glance.

Touch dimmers (or “zip” dimmers) are known in the art. A touch dimmergenerally includes a touch-operated input device, such as a resistive ora capacitive touch pad. The touch-operated device responds to the forceand position of a point actuation on the surface of the device and inturn controls the semiconductor switches of the dimmer. An example of atouch dimmer is described in greater detail in commonly-assigned U.S.Pat. No. 5,196,782, issued Mar. 23, 1993, entitled TOUCH-OPERATED POWERCONTROL, the entire disclosure of which is hereby incorporated byreference.

FIG. 2 is a cross-sectional view of a prior art touch-operated device30, specifically, a membrane voltage divider. A conductive element 32and a resistive element 34 are co-extensively supported in closeproximity by a spacing frame 36. An input voltage, V_(IN), is appliedacross the resistive element 34 to provide a voltage gradient across itssurface. When pressure is applied at a point 38 along the conductiveelement 32 (by a finger or the like), the conductive element flexesdownward and electrically contacts a corresponding point along thesurface of the resistive element 34, providing an output voltage,V_(OUT), whose value is between the input voltage V_(IN) and ground.When pressure is released, the conductive element 32 recovers itsoriginal shape and becomes electrically isolated from the resistiveelement 34. The touch-operated device 30 is characterized by a contactresistance R_(CONTACT) between the conductive element 32 and theresistive element 34. The contact resistance R_(CONTACT) is dependentupon the force of the actuation of the touch-operated device 30 and istypically substantially small for a normal actuation force.

FIG. 3 is a perspective view of a user interface of a prior art touchdimmer 40. The dimmer 40 comprises a touch-operated device 30, which islocated directly behind a faceplate 42. The faceplate 42 includes aflexible area 44 located directly above the conductive element 32 of thetouch-operated device 30 to permit a user to actuate the touch-operateddevice through the faceplate 42. A conventional phase-control dimmingcircuit is located within an enclosure 46 and controls the power from asource to a load in accordance with pressure applied to a selectablepoint on flexible area 44. The faceplate 42 may include optionalmarkings 48, 50, 52 to indicate, respectively, the location of flexiblearea 44, the lowest achievable intensity level of the load, and locationof a “power off” control. An optional LED array 54 provides a visualindication of intensity level of the load. When the load is a lightsource, there is preferably a linear relationship between the number ofilluminated LEDs and the corresponding perceived light level. Theflexible area 44 may optionally include a light transmissive areathrough which LED array 54 is visible.

It is desirable to provide the operational area, e.g., the flexible area44 of the touch dimmer 40, in an opening of a faceplate, for example, adecorator-style faceplate. An example of a decorator-style faceplate isshown and described in U.S. Pat. No. 4,835,343, issued May 30, 1989,entitled TWO PIECE FACEPLATE FOR A WALL BOX MOUNTED DEVICE, the entiredisclosure of which is hereby incorporated by reference. However, priorart touch dimmers that are provided in an opening of a faceplate havesuffered from a small operational area. Further, the operational area istypically recessed in the opening such that a user is not able toactuate the outermost edges of the operational area.

Thus, there is a need for a touch dimmer that provides a touch sensitiveoperational area in an opening of a faceplate and allows a user toactuate the touch sensitive area across the entire opening of thefaceplate. Further, there is a need for a touch dimmer that provides thetouch sensitive operational area in an opening of a faceplate, where thefront surface of the touch sensitive area is substantially flush withthe front surface of the faceplate, or protrudes through the opening adistance above the front surface of the faceplate.

SUMMARY OF THE INVENTION

According to the present invention, a load control device forcontrolling the amount of power delivered to an electrical load from anAC power source comprises a controllably conductive device, acontroller, and a touch sensitive actuator. The controllably conductivedevice is operable to be coupled in series electrical connection betweenthe source and the load. The controllably conductive device has acontrol input for controlling the controllably conductive device betweena non-conductive state and a conductive state. The controller isoperatively coupled to the control input of the controllably conductivedevice for controlling the controllably conductive device between thenon-conductive state and the conductive state. The touch sensitiveactuator has a touch sensitive front surface responsive to a pluralityof point actuations. Each of the point actuations is characterized by aposition and a force. The front surface of the touch sensitive actuatoris adapted to be provided in an opening of a faceplate such that thefront surface of the touch sensitive actuator extends through theopening at a distance equal to or greater than the depth of thefaceplate. The area defined by the front surface is substantiallycoextensive with an area defined by the opening of the faceplate. Thetouch sensitive actuator has an output operatively coupled to thecontroller for providing a control signal representative of the positionof the point actuation and responsive to the point actuation when themagnitude of the force of the point actuation is greater than a minimummagnitude. The minimum magnitude of the force of each of the pointactuations is substantially equal to at each of the respective positionson the front surface of the touch screen actuator.

According to a second embodiment of the present invention, a loadcontrol device for controlling the amount of power delivered to anelectrical load from an AC power source comprises a controllablyconductive device, a controller, and a touch sensitive actuator. Thecontrollably conductive device is operable to be coupled in serieselectrical connection between the source and the load. The controllablyconductive device has a control input for controlling the controllablyconductive device between a non-conductive state and a conductive state.The controller is operatively coupled to the control input of thecontrollably conductive device for controlling the controllablyconductive device between the non-conductive state and the conductivestate. The touch sensitive actuator comprising a front surface having afirst area and arranged in a first plane, a touch sensitive elementhaving a second area greater than the first area and arranged in asecond plane parallel to the first plane, and a force transmitterprovided between the front surface and the touch sensitive element. Thetouch sensitive element is responsive to a plurality of point actuationson the front surface of the touch sensitive actuator. Each of the pointactuations is characterized by a position and a force. The touchsensitive element comprises an output operatively coupled to thecontroller for providing a control signal representative of the positionof the point actuation. Each of the forces of the point actuations has asubstantially equal minimum magnitude at each of the respectivepositions on the front surface of the touch screen actuator.

In addition, the present invention provides a control structure for anelectrical control system for producing a variable output electricalsignal to an electrical load for controllably varying an output of saidload. The control structure comprises (1) an enclosed volume thatcontains control electronics; (2) a cover plate on one surface of saidenclosed volume having a planar front surface and having a rectangularopening therein; (3) a transparent touch pad disposed adjacent to andbehind said rectangular opening and coupled to said control electronicsand adapted to produce an output signal which is related to the positionwithin the area of said touch pad at which said touch pad is touched byan operator; (4) the width of said touch pad being greater than thewidth of said rectangular opening, whereby the side edges of said touchpad are inoperative.

Other features and advantages of the present invention will becomeapparent from the following description of the invention that refers tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a user interface of a prior art dimmer;

FIG. 2 is a cross-sectional view of a prior art touch-operated device;

FIG. 3 is a perspective view of a user interface of a prior art touchdimmer;

FIG. 4A is a perspective view of a touch dimmer according to the presentinvention;

FIG. 4B is a front view of the touch dimmer of FIG. 4A;

FIG. 5A is a partial assembled sectional view of a bezel and the touchsensitive device of the touch dimmer of FIG. 4A;

FIG. 5B is a partial exploded sectional view of the bezel and the touchsensitive device of FIG. 5A;

FIG. 6 shows the force profiles of the components and a cumulative forceprofile of the touch dimmer of FIG. 4A;

FIG. 7 is a simplified block diagram of the touch dimmer of FIG. 4A;

FIG. 8 is a simplified schematic diagram of a stabilizing circuit and ausage detection circuit of the touch dimmer of FIG. 7 according to afirst embodiment of the present invention;

FIG. 9 is a simplified schematic diagram of an audible sound generatorof the touch dimmer of FIG. 7;

FIG. 10 is a flowchart of a touch dimmer procedure executed by acontroller of the dimmer of FIG. 4A;

FIG. 11 is a flowchart of an Idle procedure of the touch dimmerprocedure of FIG. 10;

FIGS. 12A and 12B are flowcharts of an ActiveHold procedure of the touchdimmer procedure of FIG. 10;

FIG. 13 is a flowchart of a Release procedure of the touch dimmerprocedure of FIG. 10;

FIGS. 14A and 14B are simplified schematic diagrams of the circuitry fora four wire touch sensitive device and a controller of the touch dimmerof FIG. 4A according to a second embodiment of the present invention;

FIG. 15 is a simplified schematic diagram of the circuitry for a fourwire touch sensitive device and a controller of the touch dimmer of FIG.4A according to a third embodiment of the present invention;

FIG. 16A is a perspective view of a touch dimmer according to a fourthembodiment of the present invention;

FIG. 16B is a front view of the touch dimmer of FIG. 16A;

FIG. 17A is a bottom cross-sectional view of the touch dimmer of FIG.16B;

FIG. 17B is an enlarged partial view of the bottom cross-sectional viewof FIG. 17A;

FIG. 18A is a left side cross-sectional view of the touch dimmer of FIG.16B;

FIG. 18B is an enlarged partial view of the left side cross-sectionalview FIG. 18A;

FIG. 19 is a perspective view of a display printed circuit board of thedimmer of FIG. 16A;

FIG. 20 is an enlarged partial bottom cross-sectional view of a thintouch sensitive actuator according to a fifth embodiment of the presentinvention;

FIG. 21A is a perspective view of a touch dimmer according to a sixthembodiment of the present invention; and

FIG. 21B is an enlarged right side view of the touch dimmer of FIG. 21A.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing summary, as well as the following detailed description ofthe preferred embodiments, is better understood when read in conjunctionwith the appended drawings. For the purposes of illustrating theinvention, there is shown in the drawings an embodiment that ispresently preferred, in which like numerals represent similar partsthroughout the several views of the drawings, it being understood,however, that the invention is not limited to the specific methods andinstrumentalities disclosed.

FIGS. 4A and 4B are a perspective view and a front view, respectively,of a touch dimmer 100 according to the present invention. The dimmer 100includes a faceplate 102, i.e., a cover plate, having a planar frontsurface 103 and an opening 104. The opening 104 may define a standardindustry-defined opening, such as a traditional opening or a decoratoropening, or another uniquely-sized opening as shown in FIG. 4A. A bezel106 having a planar touch sensitive front surface 108 extends throughthe opening 104 of the faceplate 102. The front surface 108 of the bezel106 is positioned immediately above a touch sensitive device 110 (shownin FIGS. 5A and 5B), i.e., a touch sensitive element, such that a userof the dimmer 100 actuates the touch sensitive element 110 by pressingthe front surface 108 of the bezel 106. As shown in FIG. 4A, the frontsurface 108 of the bezel 106 is substantially flush with the frontsurface 103 of the faceplate 102, i.e., the plane of the front surface108 of the bezel 106 is coplanar with the plane of the front surface 103of the faceplate 102. However, the bezel 106 may extend through theopening 104 of the faceplate 102 such that the front surface 108 of thebezel is provided in a plane above the plane of the front surface 103 ofthe faceplate 102. The faceplate 102 is connected to an adapter 109,which is connected to a yoke (not shown). The yoke is adapted to mountthe dimmer 100 to a standard electrical wallbox.

The dimmer 100 further comprises a visual display, e.g., a plurality ofstatus markers 112 provided in a linear array along an edge of the frontsurface 108 of the bezel 106. The status markers 112 are preferablyilluminated from behind by status indicators 114, e.g., light-emittingdiodes (LEDs), located internal to the dimmer 100 (see FIG. 7). Thedimmer 100 preferably comprises a light pipe (not shown) having aplurality of light conductors to conduct the light from the statusindicators 114 inside the dimmer to the markers 112 on the front surface108 of the bezel 106. The status indicators 114 behind the markers 112are preferably blue. As shown in FIGS. 4A and 4B, the dimmer 100comprises seven (7) status markers 112. However, the dimmer 100 maycomprise any number of status markers. Further, the status markers 112may be disposed in a vertical linear array along the center of the frontsurface 108 of the bezel 106. The markers 112 may comprise shadowsapparent on the front surface 108 due to voids behind the front surface.

The front surface 108 of the bezel 106 further includes an icon 116. Theicon 116 may be any sort of visual marker, such as, for example, a dot.Upon actuation of the lower portion of the front surface 108 surroundingthe icon 116, the dimmer 100 causes a connected lighting load 208 (FIG.7) to change from on to off (and vice versa), i.e., to toggle.Preferably, a blue status indicator and an orange status indicator arelocated immediately behind the icon 116, such that the icon 116 isilluminated with blue light when the lighting load 208 is on andilluminated with orange light when the lighting load is off. Actuationof the upper portion of the front surface 108, i.e., above the portionsurrounding the icon 116, causes the intensity of the lighting load 208to change. The status indicators 114 behind the status markers 112 areilluminated to display the intensity of the lighting load 208. Forexample, if the lighting load 208 is at 50% lighting intensity, themiddle status indicator will be illuminated. Preferably, the dimmer 100does not respond to actuations in a keepout region 118 of the frontsurface 108. The keepout region 118 prevents inadvertent actuation of anundesired portion of the front surface 108 during operation of thedimmer 100.

The dimmer 100 further includes an airgap switch actuator 119. Pullingthe airgap switch actuator 119 opens a mechanical airgap switch 219(FIG. 7) inside the dimmer 100 and disconnects the lighting load 208from a connected AC voltage source 204 (FIG. 7). The airgap switchactuator 119 extends only sufficiently above the front surface 103 ofthe faceplate 102 to be gripped by a fingernail of a user. Theelectronic circuitry of the dimmer 100 (to be described in greaterdetail below) is mounted on a printed circuit board (PCB) (not shown).The PCB is housed in an enclosure (not shown), i.e., an enclosed volume,which is attached to the yoke of the dimmer 100.

FIG. 5A is a partial assembled sectional view and FIG. 5B is a partialexploded sectional view of the bezel 108 and the touch sensitive device110 of the dimmer 100 according to the present invention. The touchsensitive device 110 comprises, for example, a resistive divider, andoperates in a similar fashion as the touch-operated device 30 of theprior art touch dimmer 40. The touch sensitive device 110 includes aconductive element 120 and a resistive element 122 supported by aspacing frame 124. However, the touch sensitive device 110 may comprisea capacitive touch screen or any other type of touch responsive element.Such touch sensitive devices are often referred to as touch pads ortouch screens.

An elastomer 126 is received by an opening 128 in the rear surface ofthe bezel 106. The elastomer 126 is positioned between the bezel 106 andthe touch sensitive device 110, such that a press on the front surface108 of the bezel is transmitted to the conductive element 120 of thetouch sensitive device 110. Preferably, the elastomer 126 is made ofrubber and is 0.040″ thick. The elastomer 126 preferably has a durometerof 40 A, but may have a durometer in the range of 20 A to 80 A. Theconductive element 120 and the resistive element 122 of the touchsensitive device 110 and the elastomer 126 are preferably manufacturedfrom a transparent material such that the light from the plurality ofstatus indicators 114 inside the dimmer 100 are operable to shinethrough the touch sensitive device 110 and the elastomer 126 to frontsurface 108 of the bezel 106.

The position and size of the touch sensitive device 110 is demonstratedby the dotted line in FIG. 4B. The touch sensitive device 110 has alength L₁ and a width W₁ that is larger than a length L₂ and a width W₂of the front surface 108 of the bezel 106. Accordingly, a first area A₁of the surface of touch sensitive device 110 (i.e., A₁=L₁·W₁) is greaterthan a second area A₂ of the front surface 108 of the bezel 106 (i.e.,A₂=L₂ W₂). An orthogonal projection of the second area A₂ onto the firstarea A₁ is encompassed by the first area A₁, such that a point actuationat any point on the front surface 108 of the bezel 106 is transmitted tothe conductive element 120 of the touch sensitive device 110. As shownin FIGS. 4A and 4B, the length L₂ of the front surface 108 of the bezel106 is approximately four (4) times greater than the width W₂.Preferably, the length L₂ of the front surface 108 of the bezel 106 isfour (4) to six (6) times greater than the width W₂. Alternatively, thefront surface 108 of the bezel 106 may be provided in an opening of adecorator-style faceplate

FIG. 6 shows the force profiles of the components of the dimmer 100shown in FIGS. 5A and 5B and a cumulative force profile for the touchsensitive device 110 of the dimmer 100. Each of the force profiles showsthe force required to actuate the touch sensitive device 110 withrespect to the position of the point actuation. The force profilerepresents the amount of force required to displace the element by agiven amount. While the force profiles in FIG. 6 are shown with respectto the widths of the components of the dimmer 100, a similar forceprofile is also provided along the length of the components.

FIG. 6( a) shows a force profile of the bezel 106. The bezel 106 hassubstantially thin sidewalls 129, e.g., 0.010″ thick, such that thebezel 106 exhibits a substantially flat force profile. FIG. 6( b) showsa force profile of the touch sensitive device 110. The force required toactuate the touch sensitive device 110 increases near the edges becauseof the spacing frames 124. FIG. 6( c) shows a force profile of theelastomer 126. The force profile of the elastomer 126 is substantiallyflat, i.e., a force at any point on the front surface of the elastomer126 will result in a substantially equal force at the correspondingpoint on the rear surface.

FIG. 6( d) is a total force profile of the touch dimmer 100. Theindividual force profiles shown in FIGS. 6( a)-6(c) are additive tocreate the total force profile. The total force profile is substantiallyflat across the second area A₂ of the front surface 108 of the bezel106. This means that a substantially equal minimum actuation forcef_(MIN) is required to actuate the touch sensitive device 110 at allpoints of the front surface 108 of the bezel 106, even around the edges.Accordingly, the dimmer 100 of the present invention provides a maximumoperational area in an opening of a faceplate, i.e., substantially allof the second area A₂ of the front surface 108 of the bezel 106, whichis an improvement over the prior art touch dimmers. The minimumactuation force f_(MIN) is substantially equal at all points on thefront surface 108 of the bezel 106. For example, the minimum actuationforce f_(MIN) may be 20 grams.

FIG. 7 is a simplified block diagram of the touch dimmer 100 accordingto the present invention. The dimmer 100 has a hot terminal 202connected to an AC voltage source 204 and a dimmed hot terminal 206connected to a lighting load 208. The dimmer 100 employs a bidirectionalsemiconductor switch 210 coupled between the hot terminal 202 and thedimmed hot terminal 206, to control the current through, and thus theintensity of, the lighting load 208. The semiconductor switch 210 has acontrol input (or gate), which is connected to a gate drive circuit 212.The input to the gate renders the semiconductor switch 210 selectivelyconductive or non-conductive, which in turn controls the power suppliedto the lighting load 208. The gate drive circuit 212 provides a controlinput to the semiconductor switch 210 in response to a control signalfrom a controller 214. The controller 214 may be any suitablecontroller, such as a microcontroller, a microprocessor, a programmablelogic device (PLD), or an application specific integrated circuit(ASIC).

A zero-crossing detect circuit 216 determines the zero-crossing pointsof the AC source voltage from the AC power supply 204. A zero-crossingis defined as the time at which the AC supply voltage transitions frompositive to negative polarity, or from negative to positive polarity, atthe beginning of each half-cycle. The zero-crossing information isprovided as an input to the controller 214. The controller 214 generatesthe gate control signals to operate the semiconductor switch 210 to thusprovide voltage from the AC power supply 204 to the lighting load 208 atpredetermined times relative to the zero-crossing points of the ACwaveform. A power supply 218 generates a direct-current (DC) voltageV_(CC), e.g., 5 volts, to power the controller 214 and other low voltagecircuitry of the dimmer 100.

The touch sensitive device 110 is coupled to the controller 214 througha stabilizing circuit 220 and a usage detection circuit 222. Thestabilizing circuit 220 is operable to stabilize the voltage output ofthe touch sensitive device 110. Accordingly, the voltage output of thestabilizing circuit 220 is not dependent on the magnitude of the forceof the point actuation on the touch sensitive device 110, but rather isdependent solely on the position of the point actuation. The usagedetection circuit 222 is operable to detect when a user is actuating thefront surface 108 of the dimmer 100. The controller 214 is operable tocontrol the operation of the stabilizing circuit 220 and the usagedetection circuit 222 and to receive control signals from both thestabilizing circuit and the usage detection circuit. Preferably, thestabilizing circuit 220 has a slow response time, while the usagedetection circuit 222 has a fast response time. Thus, the controller 214is operable to control the semiconductor switch 210 in response to thecontrol signal provided by the stabilizing circuit 220 when the usagedetection circuit 222 has detected an actuation of the touch sensitivedevice 110.

The controller 214 is operable to drive the plurality of statusindicators 114, e.g., light-emitting diodes (LEDs), which are locatedbehind the markers 112 on the front surface 108 of the dimmer 100. Thestatus indicators 114 also comprise the blue status indicator and theorange status indicator that are located immediately behind the icon116. The blue status indicator and the orange status indicator may beimplemented as separate blue and orange LEDs, respectively, or as asingle bi-colored LED.

The dimmer 100 further comprises an audible sound generator 224 coupledto the controller 214, such that the controller is operable to cause thesound generator to produce an audible sound in response to an actuationof the touch sensitive device 110. A memory 225 is coupled to thecontroller 214 and is operable to store control information of thedimmer 100.

FIG. 8 is a simplified schematic diagram of the circuitry for the touchsensitive device 110 and the controller 214, i.e., the stabilizingcircuit 220 and the usage detection circuit 222, according to a firstembodiment of the present invention. The resistive element 122 of thetouch sensitive device 110 is coupled between the DC voltage V_(CC) ofthe power supply 218 and circuit common, such that the DC voltage V_(CC)provides a biasing voltage to the touch sensitive device. The resistanceof the resistive element 122 may be, for example, 7.6 kΩ. The positionof contact between the conductive element 120 and the resistive element122 of the touch sensitive device 110 is determined by the position of apoint actuation on the front surface 108 of the bezel 106 of the dimmer100. The conductive element 120 is coupled to both the stabilizingcircuit 220 and the usage detection circuit 222. As shown in FIG. 7, thetouch sensitive device 110 of the dimmer 100 of the first embodiment isa three-wire device, i.e., the touch sensitive device has threeconnections or electrodes. The touch sensitive device provides oneoutput that is representative of the position of the point actuationalong a Y-axis, i.e., a longitudinal axis of the dimmer 100 as shown inFIG. 4B.

The stabilizing circuit 220 comprises a whacking-grade capacitor C230(that is, a capacitor having a large value of capacitance) and a firstswitch 232. The controller 214 is operable to control the first switch232 between a conductive state and a non-conductive state. When thefirst switch 232 is conductive, the capacitor C230 is coupled to theoutput of the touch sensitive device 110, such that the output voltageis filtered by the capacitor C230. When a touch is present, the voltageon the capacitor C230 will be forced to a steady-state voltagerepresenting the position of the touch on the front surface 108. When notouch is present, the voltage on the capacitor will remain at a voltagerepresenting the position of the last touch. The touch sensitive device110 and the capacitor C230 form a sample-and-hold circuit. The responsetime of the sample-and-hold circuit is determined by a resistance R_(D)of the touch sensitive device (i.e., the resistance R_(E) of theresistive element and a contact resistance R_(C)) and the capacitance ofthe capacitor C230. During typical actuation, the contact resistanceR_(C) is small compared to the value of R_(E), such that a firstcharging time constant τ₁ is approximately equal to R_(E)·C₂₃₀. Thistime constant τ₁ is preferably 13 ms, but may be anywhere between 6 msand 15 ms.

When a light or transient press is applied to the touch sensitive device110, the capacitor C230 will continue to hold the output at the voltagerepresenting the position of the last touch. During the release of thetouch sensitive device 110, transient events may occur that produceoutput voltages that represent positions other than the actual touchposition. Transient presses that are shorter than the first chargingtime constant Σ₁ will not substantially affect the voltage on thecapacitor C230, and therefore will not substantially affect the sensingof the position of the last actuation. During a light press, a secondcharging time constant τ₂ will be substantially longer than duringnormal presses, i.e., substantially larger than the first time constantΣ₁, due to the higher contact resistance R_(C). However, thesteady-state value of the voltage across the capacitor C230 will be thesame as for a normal press at the same position. Therefore, the outputof the stabilizing circuit 220 is representative of only the position ofthe point of actuation of the touch sensitive device 110.

The usage detection circuit 222 comprises a resistor R234, a capacitorC236, and a second switch 238, which is controlled by the controller214. When the switch 238 is conductive, the parallel combination of theresistor R234 and the capacitor C236 is coupled to the output of thetouch sensitive device 110. Preferably, the capacitor C236 has asubstantially small capacitance C₂₃₆, such that the capacitor C236charges substantially quickly in response to all point actuations on thefront surface 108. The resistor R234 allows the capacitor C236 todischarge quickly when the switch 238 is non-conductive. Therefore, theoutput of the usage detection circuit 222 is representative of theinstantaneous usage of the touch sensitive device 110.

The controller 214 controls the switches 232, 238 in a complementarymanner. When the first switch 232 is conductive, the second switch 238is non-conductive, and vice versa. The controller 214 controls thesecond switch 238 to be conductive for a short period of time t_(USAGE)once every half cycle of the voltage source 204 to determine whether theuser is actuating the front surface 108. Preferably, the short period oftime t_(USAGE) is approximately 100 μsec or 1% of the half-cycle(assuming each half-cycle is 8.33 msec long). For the remainder of thetime, the first switch 232 is conductive, such that the capacitor C230is operable to charge accordingly. When the first switch 232 isnon-conductive and the second switch 238 is conductive, thewhacking-grade capacitor C230 of the stabilizing circuit 220 is unableto discharge at a significant rate, and thus the voltage developedacross the capacitor C230 will not change significantly when thecontroller 214 is determining whether the touch sensitive device 110 isbeing actuated through the usage detection circuit 222.

FIG. 9 is a simplified schematic diagram of the audible sound generator224 of the dimmer 100. The audible sound generator 224 uses an audiopower amplifier integrated circuit (IC) 240, for example, part numberTPA721 manufactured by Texas Instruments, Inc., to generate a sound froma piezoelectric or magnetic speaker 242. The amplifier IC 240 is coupledto the DC voltage V_(CC) (pin 6) and circuit common (pin 7) to power theamplifier IC. A capacitor C244 (preferably having a capacitance of 0.1μF) is coupled between the DC voltage V_(CC) and circuit common todecouple the power supply voltage and to ensure the output totalharmonic distortion (THD) is as low as possible.

The audible sound generator 224 receives a SOUND ENABLE signal 246 fromthe controller 214. The SOUND ENABLE signal 246 is provided to an enablepin (i.e., pin 1) on the amplifier IC 240, such that the audible soundgenerator 224 will be operable to generate the sound when the SOUNDENABLE signal is at a logic high level.

The audible sound generate 224 further receives a SOUND WAVE signal 248from the controller 214. The SOUND WAVE signal 248 is an audio signalthat is amplified by the amplifier IC 240 to generate the appropriatesound at the speaker 242. The SOUND WAVE signal 248 is first filtered bya low-pass filter comprising a resistor R250 and a capacitor C252.Preferably, the resistor R250 has a resistance of 1 kΩ and the capacitorC252 has a capacitance of 0.1 nF. The filtered signal is then passedthrough a capacitor C254 to produce an input signal V_(IN). Thecapacitor C254 allows the amplifier IC to bias the input signal V_(IN)to the proper DC level for optimum operation and preferably has acapacitance of 0.1 μF. The input signal V_(IN) is provided to a negativeinput (pin 4) of the amplifier IC 240 through a input resistor R. Apositive input (pin 3) of the amplifier IC 240 and with a bypass pin(pin 2) are coupled to circuit common through a bypass capacitor C256(preferably, having a capacitance of 0.1 μF).

The output signal V_(OUT) of the amplifier IC 240 is produced from apositive output (pin 5) to a negative output (pin 8) and is provided tothe speaker 242. The negative input (pin 4) is coupled to the positiveoutput (pin 5) through an output resistor R_(F). The gain of theamplifier IC 240 is set by the input resistor R_(I) and the feedbackresistor R_(F), i.e.,

Gain=V _(OUT) /V _(IN)=−2·(R _(F) /R _(I)).

Preferably, the input resistor R1 and the output resistor R_(F) bothhave resistances of 10 kΩ, such that the gain of the amplifier IC 240 isnegative two (−2).

FIG. 10 is a flowchart of a touch dimmer procedure 300 executed by thecontroller 214 of the dimmer 100 according to the present invention.Preferably, the touch dimmer procedure 300 is called from the main loopof the software of the controller 214 once every half cycle of the ACvoltage source 204. The touch dimmer procedure 300 selectively executesone of three procedures depending upon the state of the dimmer 100. Ifthe dimmer 100 is in an “Idle” state (i.e., the user is not actuatingthe touch sensitive device 110) at step 310, the controller 214 executesan Idle procedure 400. If the dimmer 100 is in an “ActiveHold” state(i.e., the user is presently actuating the touch sensitive device 110)at step 320, the controller 214 executes an ActiveHold procedure 500. Ifthe dimmer 100 is in a “Release” state (i.e., the user has recentlyceased actuating the touch sensitive device 110) at step 330, thecontroller 214 executes a Release procedure 600.

FIG. 11 is a flowchart of the Idle procedure 400 according to thepresent invention. The controller 114 uses a “sound flag” and a “soundcounter” to determine when to cause the audible sound generator 224 togenerate the audible sound. The purpose of the sound flag is to causethe sound to be generated the first time that the controller 214executes the ActiveHold procedure 500 after being in the Idle state. Ifthe sound flag is set, the controller 214 will cause the sound to begenerated. The sound counter is used to ensure that the controller 214does not cause the audible sound generator 224 to generate the audiblesound too often. The sound counter preferably has a maximum soundcounter value S_(MAX), e.g., 425 msec. Accordingly, there is a gap of atleast 18 half cycles between generations of the audible sound. The soundcounter is started during the Release procedure 600 as will be describedin greater detail below. Referring to FIG. 11, upon entering the Idlestate, the controller 214 sets the sound flag at step 404 if the soundflag is not set at step 402.

An “LED counter” and an “LED mode” are used by the controller 214 tocontrol the status indicators 114 (i.e., the LEDs) of the dimmer 100.The controller 214 uses the LED counter to determine when apredetermined time t_(LED) has expired since the touch sensitive device110 was actuated. When the predetermined time t_(LED) has expired, thecontroller 214 will change the LED mode from “active” to “inactive”.When the LED mode is “active”, the status indicators 114 are controlledsuch that one or more of the status indicators are illuminated to abright level. When the predetermined time t_(LED) expires, the LED modeis changed to “inactive”, i.e., the status indicators 114 are controlledsuch that one or more of the status indicators are illuminated to a dimlevel. Referring to FIG. 11, if the LED counter is less than a maximumLED counter value L_(MAX) at step 410, the LED counter is incremented atstep 412 and the process moves on to step 418. However, if the LEDcounter is not less than the maximum LED counter value L_(MAX), the LEDcounter is cleared at step 414 and the LED mode is set to inactive atstep 416. Since the touch dimmer procedure 300 is executed once everyhalf cycle, the predetermined time t_(LED) is preferably equal to

t _(LED) =T _(HALF) ·L _(MAX,)

where T_(HALF) is the period of a half cycle.

Next, the controller 214 reads the output of the usage detection circuit222 to determine if the touch sensitive device 110 is being actuated.Preferably, the usage detection circuit 222 is monitored once every halfcycle of the voltage source 204. At step 418, the controller 214 opensswitch 232 and closes switch 238 to couple the resistor R234 and thecapacitor C236 to the output of the touch sensitive device 110. Thecontroller 214 determines the DC voltage of the output of the usagedetection circuit 222 at step 420, preferably, by using ananalog-to-digital converter (ADC). Next, the controller 214 closesswitch 232 and opens switch 238 at step 422.

At step 424, if there is activity on the front surface 108 of the dimmer100, i.e., if the DC voltage determined at step 420 is above apredetermined minimum voltage threshold, then an “activity counter” isincremented at step 426. Otherwise, the activity counter is cleared atstep 428. The activity counter is used by the controller 214 todetermine if the DC voltage determined at step 420 is the result of apoint actuation of the touch sensitive device 110 rather than noise orsome other undesired impulse. The use of the activity counter is similarto a software “debouncing” procedure for a mechanical switch, which iswell known in the art. If the activity counter is not less than amaximum activity counter value A_(MAX) at step 430, then the dimmerstate is set to the ActiveHold state at step 432. Otherwise, the processsimply exits at step 434.

FIGS. 12A and 12B are flowcharts of the ActiveHold procedure 500, whichis executed once every half cycle when the touch sensitive device 110 isbeing actuated, i.e., when the dimmer 100 is in the ActiveHold state.First, a determination is made as to whether the user has stopped using,i.e., released, the touch sensitive device 110. The controller 214 opensswitch 232 and closes switch 238 at step 510, and reads the output ofthe usage detection circuit 222 at step 512. At step 514, the controller214 closes switch 232 and opens switch 238. If there is no activity onthe front surface 108 of the dimmer 100 at step 516, the controller 214increments an “inactivity counter” at step 518. The controller 214 usesthe inactivity counter to make sure that the user is not actuating thetouch sensitive device 110 before entering the Release mode. If theinactivity counter is less than a maximum inactivity counter valueI_(MAX) at step 520, the process exits at step 538. Otherwise, thedimmer state is set to the Release state at step 522, and then theprocess exits.

If there is activity on the touch sensitive device 110 at step 516, thecontroller 214 reads the output of the stabilizing circuit 220, which isrepresentative of the position of the point actuation on the frontsurface 108 of the dimmer 100. Since the switch 232 is conductive andthe switch 238 is non-conductive, the controller 214 determines the DCvoltage at the output of the stabilizing circuit 220, preferably usingan ADC, at step 524.

Next, the controller 214 uses a buffer to “filter” the output ofstabilizing circuit 220. When a user actuates the touch sensitive device110, the capacitor C230 will charge to approximately the steady-statevoltage representing the position of the actuation on the front surface108 across a period of time determined by the first time constant τ₁ aspreviously described. Since the voltage across the capacitor C230, i.e.,the output of the stabilizing circuit 220, is increasing during thistime, the controller 214 delays for a predetermined period of time atstep 525, preferably, for approximately three (3) half cycles.

When a user's finger is removed from the front surface 108 of the bezel106, subtle changes in the force and position of the point actuationoccur, i.e., a “finger roll-off” event occurs. Accordingly, the outputsignal of the touch sensitive device 110 is no longer representative ofthe position of the point actuation. To prevent the controller 214 fromprocessing reads during a finger roll-off event, the controller 214saves the reads in the buffer and processes the reads with a delay,e.g., six half cycles later. Specifically, when the delay is over atstep 525, the controller 214 rotates the new read (i.e., from step 524)into the buffer at step 526. If the buffer has at least six reads atstep 528, the controller 214 averages the reads in the fifth and sixthpositions in the buffer at step 530 to produce the touch position data.In this way, when the user stops actuating the touch sensitive device110, the controller 214 detects this change at step 516 and sets thedimmer state to the Release state at step 522 before the controllerprocesses the reads saved in the buffer near the transition time of thetouch sensitive device.

At step 532, the controller 114 determines if the touch position datafrom step 530 is in the keepout region 118 (as shown in FIG. 4B). If thetouch position data is in the keepout region 118, the ActiveHoldprocedure 500 simply exits at step 538. Otherwise, a determination ismade at step 534 as to whether the sound should be generated.Specifically, if the sound flag is set and if the sound counter hasreached a maximum sound counter value S_(MAX), the controller 214 drivesthe SOUND ENABLE signal 246 high and provides the SOUND WAVE signal 248to the audible sound generator 224 to generate the sound at step 535.Further, the sound flag is cleared at step 536 such that the sound willnot be generated as long as the dimmer 100 remains in the ActiveHoldstate.

If the touch position data is in the toggle area, i.e., the lowerportion of the front surface 108 of the bezel 106 surrounding the icon116 (as shown in FIG. 4A), at step 540, the controller 214 processes theactuation of the touch sensitive device 110 as a toggle. If the lightingload 208 is presently off at step 542, the controller 214 turns thelighting load on. Specifically, the controller 214 illuminates the icon116 with the blue status indicator at step 544 and dims the lightingload 208 up to the preset level, i.e., the desired lighting intensity ofthe lighting load, at step 546. If the lighting load is presently on atstep 542, the controller 214 turns on the orange status indicator behindthe icon 116 at step 548 and fades the lighting load 208 to off at step550.

If the touch position data is not in the toggle area at step 540, thecontroller 214 scales the touch position data at step 552. The output ofthe stabilizing circuit 220 is a DC voltage between a maximum value,i.e., substantially the DC voltage V_(CC), and a minimum value, whichcorresponds to the DC voltage providing by the touch sensitive device110 when a user is actuating the lower end of the upper portion of thefront surface 108 of the bezel 106. The controller 214 scales this DCvoltage to be a value between off (i.e., 1%) and full intensity (i.e.,100%) of the lighting load 208. At step 554, the controller 214 dims thelighting load 208 to the scaled level produced in step 552.

Next, the controller 214 changes the status indicators 114 locatedbehind the markers 112 on the front surface 108 of the bezel 106. As auser actuates the touch sensitive device 110 to change intensity of thelighting load 208, the controller 214 decides whether to change thestatus indicator 114 that is presently illuminated. Since there areseven (7) status indicators to indicate an intensity between 1% and100%, the controller 214 may illuminate the first status indicator,i.e., the lowest status indicator, to represent an intensity between 1%and 14%, the second status indicator to represent an intensity between15% and 28%, and so on. The seventh status indicator, i.e., the higheststatus indicator, may be illuminated to represent an intensity between85% and 100%. Preferably, the controller 214 uses hysteresis to controlthe status indicators 114 such that if the user actuates the frontsurface 108 at a boundary between two of the regions of intensitiesdescribed above, consecutive status indicators do not toggle back andforth.

Referring to FIG. 12B, a determination is made as to whether a change isneeded as to which status indicator is illuminated at step 556. If thepresent LED (in result to the touch position data from step 530) is thesame as the previous LED, then no change in the LED is required. Thepresent LED is set the same as the previous LED at step 558, ahysteresis counter is cleared at step 560, and the process exits at step570.

If the present LED is not the same as the previous LED at step 556, thecontroller 214 determines if the LED should be changed. Specifically, atstep 562, the controller 214 determines if present LED would change ifthe light level changed by 2% from the light level indicated by thetouch position data. If not, the hysteresis counter is cleared at step560 and the process exits at step 570. Otherwise, the hysteresis counteris incremented at step 564. If the hysteresis counter is less than amaximum hysteresis counter value H_(MAX) at step 566, the process exitsat step 570. Otherwise, the LEDs are changed accordingly based on thetouch position data at step 568.

FIG. 13 is a flowchart of the Release procedure 600, which is executedafter the controller 214 sets the dimmer state to the Release state atstep 522 of the ActiveHold procedure 500. First, a save flag is set atstep 610. Next, the sound counter is reset at step 612 to ensure thatthe sound will not be generated again, e.g., for preferably 18 halfcycles. At step 618, a determination is made as to whether the dimmer100 is presently executed a fade-to-off. If not, the present level issaved as the preset level in the memory 225 at step 620. Otherwise, thedesired lighting intensity is set to off at step 622, the long fadecountdown in started at step 624, and the preset level is saved as offin the memory 225.

FIG. 14A and FIG. 14B are simplified schematic diagrams of the circuitryfor a four-wire touch sensitive device 710 and a controller 714according to a second embodiment of the present invention. The four-wiretouch sensitive device 710 has four connections, i.e., electrodes, andprovides two outputs: a first output representative of the position of apoint actuation along the Y-axis, i.e., the longitudinal axis of thedimmer 100 a shown in FIG. 4B, and a second output representative of theposition of the point actuation along the X-axis, i.e., an axisperpendicular to the longitudinal axis. The four-wire touch sensitivedevice 710 provides the outputs depending on how the DC voltage V_(CC)is connected to the touch sensitive device. A stabilizing circuit 720 isoperatively coupled to the first output and a usage detection circuit722 is operatively coupled to the second output.

The controller 714 controls three switches 760, 762, 764 to connect thetouch sensitive device 710 to the DC voltage V_(CC) accordingly. Whenthe switches 760, 762, 764 are connected in position A as shown in FIG.14A, the DC voltage V_(CC) is coupled across the Y-axis resistor, andthe X-axis resistor provides the output to the stabilizing circuit 720.When the switches 760, 762, 764 are connected in position B as shown inFIG. 14B, the DC voltage V_(CC) is coupled across the X-axis resistor,and the Y-axis resistor provides the output to the usage detectioncircuit 722. Since the controller 714 provides one output signal tocontrol whether the stabilizing circuit 720 or the usage detectioncircuit 722 is coupled to the touch sensitive device 110, the softwareexecuted by the controller 714 is the same as the software executed bythe controller 214 shown in FIGS. 10-13.

FIG. 15 is a simplified schematic diagram of the circuitry for thefour-wire touch sensitive device 710 and a controller 814 according to athird embodiment of the present invention. The controller 814 isoperable to read the position of a point actuation on the four-wiretouch sensitive device 710 along both the Y-axis and the X-axis. Whendetermining the position along the Y-axis, the controller 814 operatesthe same as the controller 714 shown in FIGS. 14A and 14B by controllingthe switches 760, 762, 764 as described above.

An additional stabilizing circuit 870 is provided for determining theposition of the point actuation along the X-axis. The additionalstabilizing circuit 870 comprises a whacking-grade capacitor C872. Thecontroller 814 controls a switch 874 to selectively switch the output ofthe X-axis between the usage detection circuit 722 and the additionalstabilizing circuit 870. The controller 814 controls the switch 874 in asimilar fashion to how the controller 214 controls the switches 232, 238(as shown in FIG. 8).

FIGS. 16A and 16B are a perspective view and a front view, respectively,of a touch dimmer 900 according to a fourth embodiment of the presentinvention. FIG. 17A is a bottom cross-sectional view and FIG. 17B is anenlarged partial bottom cross-sectional view of the dimmer 900. FIG. 18Ais a left side cross-sectional view and FIG. 18B is an enlarged partialleft side cross-sectional view of the dimmer 900.

The touch dimmer 900 includes a thin touch sensitive actuator 910comprising an actuation member 912 extending through a bezel 914. Thedimmer 900 further comprises a faceplate 916, which has a non-standardopening 918 and mounts to an adapter 920. The bezel 914 is housed behindthe faceplate 916 and extends through the opening 918. The adapter 920connects to a yoke 922, which is adapted to mount the dimmer 900 to astandard electrical wallbox. A main printed circuit board (PCB) 924 ismounted inside an enclosure 926 and includes the some of the electricalcircuitry of the dimmer 200, e.g., the semiconductor switch 210, thegate drive circuit 212, the controller 214, the zero-crossing detectcircuit 216, the power supply 218, the stabilizing circuit 220, theusage detection circuit 222, the audible sound generator 224, and thememory 225, of the dimmer 200. The thin touch sensitive actuator 910preferably extends beyond the faceplate by 1/16″, i.e., has a height of1/16″, but may have a height in the range of 1/32″ to 3/32″. Preferably,the touch sensitive actuator 910 has a length of 3⅝″ and a width of3/16″. However, the length and the width of the touch sensitive actuator910 may be in the ranges of 2⅝″-4″ and ⅛″-¼″, respectively.

The touch sensitive actuator 910 operates to contact a touch sensitivedevice 930 inside the touch dimmer 900. The touch sensitive device 930is contained by a base 932. The actuation member 912 includes aplurality of long posts 934, which contact the front surface of thetouch sensitive device 930 and are arranged in a linear array along thelength of the actuation member. The posts 934 act as force concentratorsto concentrate the force from an actuation of the actuation member 912to the touch sensitive device 930.

A plurality of status indicators 936 are arranged in a linear arraybehind the actuation member 912. The status indicators are mounted on adisplay PCB 938, i.e., a status indicator support board, which ismounted between the touch sensitive device 930 and the bezel 914. FIG.19 is a perspective view of the display PCB 938. The display PCB 938includes a plurality of holes 939, which the long posts 934 extendthrough to contact the touch sensitive device 930. The actuation member912 is preferably constructed from a translucent material such that thelight of the status indicators 936 is transmitted to the surface of theactuation member. A plurality of short posts 940 are provided in theactuation member 912 directly above the status indicators 936 to operateas light pipes for the linear array of status indicators. The displayPCB 938 comprises a tab 952 having a connector 954 on the bottom sidefor connecting the display PCB 938 to the main PCB 924.

The actuation member 912 comprises a notch 942, which separates a lowerportion 944 and an upper portion 946 of the actuation member. Uponactuation of the lower portion 944 of the actuation member 912, thedimmer 900 causes the connected lighting load to toggle from on to off(and vice versa). Preferably, a blue status indicator 948 and an orangestatus indicator 950 are located behind the lower portion 944, such thatthe lower portion is illuminated with blue light when the lighting loadis on and illuminated with orange light with the lighting load is off.Actuation of the upper portion 946 of the actuation member 912, i.e.,above the notch 942, causes the intensity of the lighting load to changeto a level responsive to the position of the actuation on the actuationmember 912. The status indicators 936 behind the status markers 112 areilluminated to display the intensity of the lighting load as with thepreviously-discussed touch dimmer 100.

FIG. 20 is an enlarged partial bottom cross-sectional view of a thintouch sensitive actuator 960 according to a fifth embodiment of thepresent invention. The touch sensitive actuator 960 comprises anactuation member 962 having two posts 964 for actuating the touchsensitive device 930. A plurality of status indicators 966 are mountedon a flexible display PCB 968, i.e., a flexible status indicator supportboard, which the posts 964 of the actuation member 962 are operable toactuate the touch sensitive device 930 through. The status indicators966 are preferably blue LEDs and are arranged along the length of theactuation member 962. Preferably, the actuation member 962 isconstructed from a translucent material such that the light of thestatus indicators 966 is transmitted to the surface of the actuationmember.

FIG. 21A is a perspective view and FIG. 21B is an enlarged side view ofa touch dimmer 1000 according to a sixth embodiment of the presentinvention. The dimmer 1000 comprises a bezel 1010 having a front surface1012 and a faceplate 1014 having an opening 1016. Actuation of the frontsurface 1012 actuates a touch sensitive device (not shown) inside thedimmer (in a similar fashion as the dimmer 100). The dimmer 1000 furthercomprises a shallow domed protrusion 1018, i.e., a raised area, on thefront surface 1012 of the bezel 1010. Actuation of the shallow domedprotrusion 1018 causes the dimmer 1000 to toggle a connected lightingload (not shown) from off to on (and vice versa). Actuation of an upperportion 1020 of the front surface 1012 of the bezel 1010 above the domeprotrusion 1018 causes the dimmer 1000 to change the intensity of thelighting load. The dimmer 1000 further comprises a status indicator,e.g., an LED, immediately behind the shallow domed protrusion 1018 toilluminate the protrusion.

Preferably, a keepout region 1022 is provided between the domeprotrusion 1018 and the upper portion 1020 of the front surface 1012 ofthe bezel 1010. The dimmer 1000 does not respond to actuations of thekeepout region 1022. Accordingly, a portion of the touch sensitivedevice immediately below the domed protrusion 1018, i.e., the “toggleactuator”, and the upper portion 1020 is disabled to provide the keepoutregion 1022.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

1. A user interface for a load control device, the user interface beingadapted to be positioned in an opening of a faceplate, the userinterface comprising: a touch sensitive front surface and adapted to beprovided in the opening of the faceplate; and a touch sensitive device,responsive to a point actuation on the touch sensitive front surface,the point actuation comprising characteristics of a position and aforce, the touch sensitive device having an output for providing acontrol signal representative of the position of the point actuation;wherein the touch sensitive device defines a first area and the touchsensitive front surface defines a second area, the first area of thetouch sensitive device being larger than the second area of the touchsensitive front surface, the touch sensitive device and touch sensitivefront surface being positioned such that an orthogonal projection of thesecond area of the touch sensitive front surface onto the first area ofthe touch sensitive device is encompassed by the first area.
 2. The userinterface of claim 1, further comprising: an actuation member definingthe touch sensitive front surface and adapted to be actuated with thepoint actuation, the actuation member adapted to be received in theopening of the faceplate and positioned such that the actuation memberis operable to contact the touch sensitive device and to concentrate theforce of the point actuation onto the touch sensitive device.
 3. Theuser interface of claim 2, wherein the actuation member comprises apost, operable to transmit the force of the point actuation onto thetouch sensitive device.
 4. The user interface of claim 3, wherein theactuation member is provided along a longitudinal axis of the userinterface, and the touch sensitive device extends along the longitudinaldirection for substantially the length of the actuation member.
 5. Theuser interface of claim 4, further comprising: a plurality of statusindicators located between the touch sensitive device and the actuationmember.
 6. The user interface of claim 5, wherein the actuation membercomprises a translucent material with the actuation member operating asa light pipe for the status indicators.
 7. The user interface of claim6, further comprising: a printed circuit board located between the touchsensitive device and the actuation member, the status indicators mountedin a linear array on the printed circuit board.
 8. The user interface ofclaim 7, wherein the printed circuit board comprises a plurality ofholes arranged along the longitudinal axis of the user interface; andfurther wherein the actuation member comprises a plurality of firstposts extending in a linear array along the longitudinal axis of theuser interface for substantially the length of the actuation member, theplurality of first posts being operable to extend through the pluralityof holes of the printed circuit board, such that the actuation member isoperable to transmit the force of the point actuation onto the touchsensitive device.
 9. The user interface of claim 1, further comprising:a bezel defining the touch sensitive front surface, the bezel adapted toextend through the opening of the faceplate; and a force transmitterprovided between the bezel and the touch sensitive device, the forcetransmitter operable to transmit the force of the point actuation on thetouch sensitive front surface to the touch sensitive device.
 10. Theuser interface of claim 9, wherein the force transmitter has asubstantially constant force profile.
 11. The user interface of claim10, wherein the force transmitter comprises an elastomer.
 12. The userinterface of claim 9, wherein the touch sensitive device is provided ina first plane and the touch sensitive front surface is provided in asecond plane substantially parallel with the first plane.
 13. The userinterface of claim 12, wherein the touch sensitive front surface isadapted to be substantially flush with the front surface of thefaceplate.
 14. The user interface of claim 9, further comprising: aplurality of status indicators arranged in a linear array behind theforce transmitter; wherein the force transmitter is comprised of atransparent material such that the status indicators are operable toshine through the force transmitter and onto the touch sensitive frontsurface.
 15. The user interface of claim 9, wherein the bezel comprisessidewalls, the force transmitter located between the sidewalls of thebezel.
 16. The user interface of claim 9, wherein a total force profileof the user interface is substantially constant across the second areaof the touch sensitive front surface.
 17. The user interface of claim 1,wherein the force profile of the touch sensitive device is substantiallyconstant across the orthogonal projection of the second area onto thefirst area.
 18. The user interface of claim 1, wherein the touchsensitive device has edges, and a force, required to actuate the touchsensitive device, being substantially greater in an area near the edges;and wherein the area near the edges comprises the portion of the firstarea outside of the orthogonal projection of the second area on thefirst area.
 19. A load control device for controlling the amount ofpower delivered to an electrical load from an AC power source, the loadcontrol device comprising: a controllably conductive device operable tobe coupled in series electrical connection between the source and theload, the controllably conductive device having a control input forcontrolling the controllably conductive device between a non-conductivestate and a conductive state; a controller operatively coupled to thecontrol input of the controllably conductive device for controlling thecontrollably conductive device between the non-conductive state and theconductive state; a touch sensitive front surface adapted to be providedin an opening of a faceplate; and a touch sensitive device responsive toa point actuation on the touch sensitive front surface, the pointactuation comprising characteristics of a position and a force, thetouch sensitive device having an output operatively coupled to thecontroller for providing a control signal representative of the positionof the point actuation; wherein the touch sensitive device defines afirst area and the touch sensitive front surface defines a second area,the first area of the touch sensitive device being larger than thesecond area of the touch sensitive front surface, the touch sensitivedevice and touch sensitive front surface being positioned such that anorthogonal projection of the second area of the touch sensitive frontsurface onto the first area of the touch sensitive device is encompassedby the first area.
 20. A user interface for a load control device, theuser interface comprising: a bezel defining a touch sensitive frontsurface, the touch sensitive front surface being provided in a firstplane and defining a first area, the bezel operable to extend throughthe opening of a faceplate, such that the touch sensitive front surfaceis positioned substantially coextensive with the opening of thefaceplate or slightly beyond a front surface of the faceplate; a touchsensitive device positioned in a second plane, parallel with the firstplane, and defining a second area larger than the first area, the touchsensitive device responsive to a plurality of point actuations on thetouch sensitive front surface, each point actuation a position and aforce, the touch sensitive device having an output for providing acontrol signal representative of the position of the point actuation andresponsive to the point actuation when the magnitude of the force of thepoint actuation is greater than a minimum magnitude; and a forcetransmitter positioned between the bezel and the touch sensitive deviceand having a substantially constant force profile, the force transmitteroperable to transmit the force of the point actuation, on the touchsensitive front surface, to the touch sensitive device.